A230528 Numbers k such that a shortest addition chain for 2*k is shorter than one for k, that is, A003313(2*k) < A003313(k).

375494703, 602641031, 619418303, 728117339, 750793519, 750832687, 750989359

Offset: 1

Author

Max Alekseyev, Oct 22 2013

Keywords

• nonn
• hard
• more
• nice

Comments

Can the shortest addition chain for 2*k be shorter than one for k by more than 1? - Alexey Slizkov, Jan 20 2024

Links

• Neill Michael Clift, Calculating optimal addition chains, Computing 91.3 (2011): 265-284.
• V. Zhuravlev and P. Samovol, Faster than the fastest, or can one beat the binary algorithm, Kvant 2 (2013), 7-15. (in Russian)

Crossrefs

Cf. A003313, A086878, A115016, A256653.

Extensions

a(1) = 375494703 was found by Neill M. Clift (2011)

a(2)-a(7) from Hugo Pfoertner, Dec 19 2015